RE 12" SXX Box

[gckless]

An RE SXX 12" is on it's way to my house now, and I'm trying to design a box for it now. I'm using WinISD now, and trying to get a good box designed before I start cutting wood. RE Audio recommends 2 cubic feet at 35Hz, but I want to tune a bit lower, around 31 or 32Hz. So because of the size of my trunk, I'm pretty set on the following for dimensions:

15"H x 19"W x 15"L (length being depth in this case)
These are all inside dimensions.

Where I need help is the port. Using WinISD, the best I have found is this:

2"W x 15"H x 28"D
This gives me a tuning frequency at or just a bit below 31Hz, and a Vent Mach of .07.

This is my first quality build, so I'm looking to get it right the first time, as I don't want to be building another box for this driver because I could have done a better job the first time. Any/all help is appreciated.

[gckless]

Or should I go with two 3" round ports, 14" each? This is fairly confusing to me. Ultimately, I'm looking for the easiest and cheapest way, while still retaining sound quality. I don't have access to any tools really, I don't want to go out and buy saws just for this one sub box, so I will more than likely end up providing dimensions and plans to someone to have them cut the wood for me, though I will assemble it myself.

[RSDXzec]

if you're going cheap then go for square/rectangle ports, I've gone with square ports on both of the boxes I've designed just because I don't have the tools to cut the perfect circles needed to put in a round port. You also make use of any left over wood from the sheet you buy so there's no need to buy the ports separately